A wildfire burning along the Highway 29 is seen through a fire truck Thursday, Oct. 12, 2017, near Calistoga, Calif. More than 8,000 firefighters are battling the blazes and additional manpower and equipment was pouring in from across the country and as far as Australia and Canada. (AP Photo/Jae C. Hong)

CORRECTS TO REMOVE REFERENCE OF WINERY - Leaves hang to a grapevine that was burned by a massive wildfire Thursday, Oct. 12, 2017, in Sonoma, Calif. Gusting winds and dry air forecast for Thursday could drive the next wave of devastating wildfires that are already on their way to becoming the deadliest and most destructive in California history. (AP Photo/Rich Pedroncelli)

A wildfire burns along the Highway 29 Thursday, Oct. 12, 2017, near Calistoga, Calif. Officials say progress is being made in some of the largest wildfires burning in Northern California but that the death toll is almost sure to surge. (AP Photo/Jae C. Hong)

A firefighter gestures to his colleagues as he walks through thick smoke from a wildfire Thursday, Oct. 12, 2017, near Calistoga, Calif. (AP Photo/Jae C. Hong)

A firefighter puts out a hot spot from a wildfire Thursday, Oct. 12, 2017, near Calistoga, Calif. Officials say progress is being made in some of the largest wildfires burning in Northern California but that the death toll is almost sure to surge. (AP Photo/Jae C. Hong)

Santa Paula firefighter Tyler Zeller, right, hoses down a hot spot with the help of Jesse Phillips, Thursday, Oct. 12, 2017, in Sonoma, Calif. Firefighters from across the state have been brought in to help battle the blazers that started Sunday night. (AP Photo/Rich Pedroncelli)

SONOMA, Calif. (AP) — The Latest on wildfires in California (all times local):

6:15 p.m.

Northern California's wildfires have now killed 31 people — making this the deadliest week of wildfires in state history.

Sonoma County Sheriff Robert Giordano said Thursday night that two more people have been confirmed dead there. That raises the statewide death total from 29 to 31.

The Oakland Hills fire of 1991 killed 25 people by itself, and the Griffith Park fire in Los Angeles in 1933 killed 29.

While no single fire currently burning has killed as many as those, state fire Deputy Director Daniel Berlant says collectively this is the deadliest series of simultaneous fires in the state in recorded history.

The blazes, most of them in wine country, broke out almost all at once on Sunday night.

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4:10 p.m.

California's deadly wildfires have claimed the home of 'Peanuts' creator Charles Schulz but his widow has escaped the flames.

Officials say progress is being made in some of the largest wildfires burning in Northern California but that the death toll is almost sure to surge.

Fire Chief Ken Pimlott says the number of dead is 26 as of Thursday.

Pimlott says crews have made significant progress against blazes in the foothills of the Sierra Nevada and they're being redirected to wine country.

He says the fires blackening California's wine country are threatening dozens of communities and larger cities and that erratic wind gusts are expected in the area starting Friday.

More than 8,000 firefighters are battling the blazes and additional manpower and equipment was pouring in from across the country and as far as Australia and Canada.

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11:15 a.m.

California fire officials are investigating downed power lines and other utility equipment failures as possible causes of massive wildfires sweeping through wine country.

California Department of Forestry and Fire Protection spokeswoman Janet Upton says it's unclear if downed power lines and live wires resulted from fires or started them.

She said Thursday that investigators are looking into that and other possible causes.

Jennifer Robison of Pacific Gas and Electric Co. says the utility is focused on restoring power and maintaining safety. She says they will not speculate about the causes of the fires.

She says PG&E will support reviews by any regulator or agency.

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10:15 a.m.

Officials say recovery teams, some with cadaver dogs, will start searching for bodies in some areas devastated by wildfires raging in California wine country.

Sonoma County Sheriff Robert Giordano says officials are investigating hundreds of reports of missing people and that recovery teams will start doing targeted searches for bodies Thursday. He warns that identification may be difficult and take some time.

He says officials have found some bodies almost completely intact but other remains are "nothing more than ash and bones."

Giordano says at least 14 people have been killed Sonoma County, raising the death toll to 24.

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9:30 a.m.

One of the California counties hard hit by wildfires this week chose not to use one type of emergency alert service to warn residents of possible danger.

Spokeswoman Jennifer Larocque says Sonoma County considered but did not use the Wireless Emergency Alert which sends a widespread message to cell phones and is sometimes likened to an Amber Alert.

Larocque says because of its broad reach officials concluded the message could panic people who were not in danger and trigger unnecessary evacuations that would snarl traffic and delay emergency vehicles.

Sonoma County did use another emergency alert service that texted thousands of warnings to residents to flee Sunday night. However, nearly 80 cellphone towers were knocked out or badly damaged.

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7:55 a.m.

Officials say fire crews have made progress on one of 22 fires burning in Northern California.

Department of Forestry and Fire Protection spokesman Daniel Berlant said Thursday a blaze burning in Napa and Sonoma Counties is 10 percent contained.

But he warns that potential gusty winds forecast to hit the area later in the day could hamper firefighting efforts.

Blazes burning in three other Northern California counties have killed 10 people.

Entire cities have evacuated in anticipation of the next round of flames, their streets empty and the only motion coming from ashes falling like snowflakes.

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7:15 a.m.

A fire official says blazes burning in Northern California grew a bit overnight but it was not as dramatic as prior days.

However, that could change Thursday as winds gusting to 45 mph (72 kph) and dry air are expected to pummel areas north of San Francisco where at least 23 people have died and at least 3,500 homes and businesses have been destroyed.

California Department of Forestry and Fire Protection spokesman Scott McLean told Oakland television station KTVU that winds were calm early Thursday and firefighters had made some gains overnight.

Thousands of firefighters are battling at least 22 fires spanning more than 265 square miles (686 square kilometers) for a fourth day.

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6:10 a.m.

Officials believe at least 111 rural homes have been destroyed in a wildfire that is chewing through brush and timber on the western slope of the Sierra Nevada in California.

It's one of more than 20 deadly and destructive fires burning across California.

Yuba County spokesman Russ Brown said Thursday that damage estimates are preliminary and crews have had a hard time getting into mountain communities to survey burn areas.

Brown says overnight winds lessened somewhat, giving firefighters an edge as they beat back the fire that broke out Sunday north of Sacramento.